Diorganodihalosilanes are hydrolyzed to produce a wide range of polyorganosiloxanes, which are sold into many different industries. Typically, diorganodihalosilanes are produced commercially by the Mueller-Rochow Direct Process, which comprises passing an organohalide, such as methyl chloride, over zero-valent silicon in the presence of a copper catalyst and various promoters to produce a mixture of organohalosilanes. Of the organhalosilanes produced in the Direct Process, dimethyldichlorosilane is the most valuable.
A typical commercial process to make zero-valent silicon comprises the carbothermic reduction of SiO2 in an electric arc furnace at extremely high temperatures. Generation of these extreme temperatures requires significant amounts of energy, which adds significant cost to the process of producing zero-valent silicon. Consequently, the use of zero-valent silicon also adds significant costs to the production of diorganodihalosilanes.
In addition to the Direct Process, diorganodihalosilanes have been produced by the alkylation of silicon tetrachloride and various methylchlorosilanes by passing the vapors of these chlorosilanes together with an alkyl halide over finely divided aluminum or zinc at elevated temperatures. However, this process results in the production of a large amount of aluminum chloride or zinc chloride, which is costly to dispose of on a commercial scale.
Therefore, there is a need for a more economical method of producing diorganodihalosilanes that avoids the need for zero-valent silicon produced by reducing SiO2 at extremely high temperatures and that does not require the costly disposal of byproducts.